This invention relates to an exhaust system for marine vessels such as yachts and smaller boats with inboard engines and particularly to a system for the underwater discharge of exhaust gases and the separation of exhaust gases and water prior to discharge from the system at running speeds.
Marine vessels such as yachts and boats incorporate gas or diesel engines for propulsion. Such engines produce foul smelling exhaust gases, soot and a significant level of engine noise. A challenge in the design of pleasure boats and yachts is to simnultaneously efficiently discharge such exhausts from the engines, minimize the passenger's contact with a such exhaust gases and reduce engine noise.
One solution to the engine noise problem is to provide a muffler which receives the exhaust gases and discharges the gas from the boat above the waterline. It is also known to discharge the exhaust gases below the waterline or a combination of above and below the waterline. Known mufflers include a dry system that uses baffles to muffle the sound and wet systems that mix water drawn in through a hull fitting with the exhaust gases. Typically, the water is mixed with the hot exhaust gases and then simultaneously discharged from the boat through a single common outlet. Below the waterline discharge systems provide a more effective means for muffling the engine noise than above the waterline systems except that an underwater system can result in back pressure for the engines and "burping" of the gases at idle or slow speeds.